1. Field of the Invention
This invention relates to a continuous process for producing polychloroisocyanuric acid compounds. Polychloroisocyanuric acid compounds are well known products used in laundry, bleaching and sanitizing applications.
2. Brief Description of the Prior Art
It has long been a desire to produce polychloroisocyanuric acid compounds commercially in a process which eliminates or minimizes the formation of effluents containing both available chlorine as hypochlorite ions and chloride ions. These effluents, which are produced in large volumes, can be re-used to some extent, however, a large portion of the volume of effluent must be treated to convert the available chlorine (hypochlorite ions) to chloride ions by one of several known methods.
In the production of polychloroisocyanuric acids, i.e., dichloroisocyanuric acid and trichloroisocyanuric acid, by the reaction of chlorine with aqueous slurries of alkali metal cyanurates, it is recognized that dilute concentrations of hypochlorous acid, formed in situ, serve as the chlorinating agent. However, in addition, equimolar amounts of hydrochloric acid are produced as a by-product.
The preparation of chloroisocyanuric acids by the reaction of hypochlorous acid with cyanuric acid has been proposed in U.S. Pat. No. 3,712,891 by S. Berkowitz, published Jan. 23, 1973. The patent proposes to react hypochlorous acid solutions having a pH in the range of 3.5-5.0 with cyanuric acid in an aqueous medium at a temperature of 0.degree.-50.degree. C. The process employs dilute solutions of impure hypochlorous acid which result in the formation of large volumes of aqueous effluents containing available chlorine and ionic impurities which have to be used or treated prior to disposal. In addition, operating at pH's above 3 results in reduced reactivity of the hypochlorous acid as well as the release of chlorine-containing gases.
The production of large volumes of dilute solutions containing available chlorine, and usually hydrochloric acid, poses a disposal problem which results in substantial increases in the operating costs for the process. These cost increases are such that they offset the advantages gained by employing dilute hypochlorous acid solutions as a reactant to produce chloroisocyanuric acid solutions which are free of a by-product salt.
Now it has been found that polychloroisocyanuric acids can be produced directly in a single step process without forming a by-product salt and without producing large volumes of dilute effluents containing available chlorine for re-use or disposal.